1. Field of the Invention
The present invention generally relates to a method for stimulating the production of thyroid stimulating hormone (TSH) and enhancing thyroid function in animals. More particularly, the present invention relates to a method for treatment of hypothyroidism.
2. Background of the Prior Art
Cyclic 3',5'-adenosine monophosphate (cyclic AMP) is now recognized as a versatile regulatory agent which acts to control the rate of a number of cellular processes. It occurs in virtually all animal species.
It is now believed that thyrotropin releasing hormone (TRH) produced in the hypothalmus stimulates adenyl cyclase (an enzyme which produces cyclic AMP in the body from adenosine triphosphate) in the thyrotropic cells of the anterior pituitary gland. The resulting rise in the level of cyclic AMP in these cells stimulates the release of thyroid-stimulating hormone (TSH), which then stimulates adenyl cyclase in the thyroid gland. This results in an increase in the level of cyclic AMP which in turn increases the synthesis and the release of thyroid hormone.
In vitro stimulation of thyroid stimulating hormone (TSH) release from the pituitary gland by exogenous cyclic AMP or its dibutyryl derivative, N.sup.6,2'0-dibutyryl cyclic AMP (DBC) has been heretofore shown. It has also been shown that in vitro administration of exogenous cyclic AMP or DBC stimulates synthesis and release of thyroidal hormone from the thyroid gland. However, in vivo studies even with very high doses of cyclic AMP have shown only a small effect on thyroidal function.
Hypothyroidism is a condition resulting from deficiency of thyroid activity. Hypothyroidism is treatable with human thyroid stimulating hormone (TSH), but long-term treatment can result in undesirable side effects. Hypothyroidism is also treatable with extracts of animal thyroid glands. However, not all hypothyroid persons respond to this treatment and there are also undesirable side effects.